Solid polymer fuel cell with reactant air humidified by a processed water tank

ABSTRACT

A water tank  21  for stocking processed water used for cooling of a solid polymer type fuel cell  6 , etc., cooling water supply means for supplying the processed water to the fuel cell  6  reactant air supplying means for supplying the reactant air to the fuel cell  6 , and fuel gas supply means for electrode reaction are provided, and the reactant air supply means passes the reactant air through the water tank  21  to add moisture to the gas.

TECHNICAL FIELD

The present invention relates to a solid polymer type fuel cell forhumidifying reactant air (air) to be supplied to an air electrode of thesolid polymer type fuel cell.

There has been recently a fuel cell power generating system in whichfuel is promoted to make an electrochemical reaction and electric energyis directly picked up by flow of electrons generated at the time of theelectrochemical reaction. The fuel cell power generating system convertsthe chemical energy possessed by fuel such as natural gas, city gas,methanol, propane gas or the like (hereinafter referred to as fuel gas)to electric energy, and it comprises a fuel-cell main body, an apparatusfor generating hydrogen from fuel, an apparatus for converting DC outputgenerated in the fuel-cell main body to alternating current, a heatexchanger for keeping the temperature of the reactant air to atemperature suitable for the operation of the fuel-cell main body andoccurrence of hydrogen, etc.

In such a fuel cell power generating system, fuel gas such as naturalgas, city gas, methanol or the like is subjected to steam reforming(chemical reaction) under the action of reforming catalyst filled in areformer to generate reformed gas containing hydrogen as a maincomponent. The reformed gas is supplied to a CO shift converter toconvert carbon monoxide contained in the reformed gas to carbon dioxide,and then the concentration of the residual carbon monoxide is reduced toa predetermined concentration value or less in a CO remover. Hydrogenthus achieved makes an electrochemical reaction with oxygen contained inair in the fuel-cell main body to perform power generation. Solidpolymer type fuel cell has been proposed as a fuel cell used in such afuel cell power generating system as described above.

The fuel-cell main body of the solid polymer type fuel cell comprises afuel electrode to which reformed gas is supplied, an air electrode towhich reactant air (air) is supplied and an electrolyte membrane (ionexchange membrane). At the fuel electrode side of the solid polymer typefuel cell thus constructed, the fuel electrode side of the membrane isliable to be dried because water molecules pass through the ion exchangemembrane by an electroendosmosis effect little by little when ionizedhydrogen moves through the ion electrolyte membrane (ion exchangemembrane). In order to prevent this, the reformed (hydrogen) gas isadded with water and supplied to the electrode to humidify the ionexchange membrane.

Further, at the air electrode side of the membrane, in addition toleaching of water due to the electroendosmosis, water is generatedthrough the reaction between hydrogen ions passing through the membraneand the oxygen, and the electrode is wetted with the water thusgenerated to obstruct diffusion of oxygen, so that there is a tendencythat the power generation performance is reduced. Such water can beremoved by gas for electrode reaction (hereinafter referred to asreactant air) supplied to the air electrode, however, the evaporationamount of water is increased due to flow of a large amount of air andthus the ion exchange membrane is dried. In order to prevent this, thefuel cell is specially equipped with a dedicated humidifier for applyingmoisture to the air and then supplying the humidified air to the airelectrode to thereby prevent the ion exchange membrane from being dried.

As described above, it is necessary to perform moisture management onreformed gas and reactant air (air) being used in the solid polymer typefuel cell. Therefore, in order to supply such gas for electrodereaction, there has been hitherto needed a dedicated external humidifierhaving a mechanism for heating water in a heater to generate steam orthe like and a large amount of processed water for humidification, andalso there has been needed a heat exchanger to withdraw water for thehumidifier and a dedicated water resupply device for successivelyresupplying processed water to the humidifier.

Accordingly, the present invention has been implemented to overcome theproblem of the prior art described above, and has an object to provide asolid polymer type fuel cell in which reactant gas to be used in anelectrode is moisturized and then supplied to the electrode with asimple mechanism while using existing equipment possessed by the fuelcell.

SUMMARY OF THE INVENTION

The present invention is characterized by a solid polymer type fuel cellcomprising: a fuel-cell main body for performing power generationthrough the electrochemical reaction between hydrogen in reformed gasand oxygen in reactant air; a reactant air supply portion for supplyingthe reactant air to the fuel-cell main body; a reformed gas supplyportion for supplying the reformed gas to the fuel-cell main body; and aprocessed water supply portion for supplying processed water, whereinthe processed water supply portion supplies the processed water to thereformed gas supply portion to humidify the reformed gas, humidifies thereactant air supplied from the reactant air supply portion by using theprocessed water, and then supplying the humidified reactant air to thefuel-cell main body.

The present invention further comprises a cooling portion forcirculating the processed water from the processed water supply portionto the fuel-cell main body to cool the fuel-cell main body.

In the present invention, the processed water supply portion comprises awater tank in which water is stocked, and a liquid level control portionfor keeping the water level of processed water in a predetermined rangeso that a gas-phase portion is formed in the water tank at all times,the reactant air from the reactant air supply portion being humidifiedwhile passing through the water tank and supplied to the fuel-cell mainbody.

In the present invention, the liquid level control portion comprises awater level gauge for detecting the water level of the processed waterand a motor operated valve for controlling supply of the processed waterfrom a processed water source into the processed water tank.

In the present invention, the processed water supply portion comprises aprocessed water tank in which processed water is stocked, andtemperature adjusting means for keeping the temperature of the processedwater in the processed water tank in a predetermined range, wherein thedegree of humidification is adjusted by a set temperature when thereactant air from the reactant air supply portion is humidified whilepassing through the processed water tank.

In the present invention, the upper limit value of the predeterminedrange of the processed water to be adjusted by the temperature adjustingmeans is varied in accordance with the operation temperature of the fuelcell.

In the present invention, the predetermined temperature range of theprocessed water to be adjusted by the temperature adjusting means rangesfrom 60° C. to 80° C.

In the present invention, the temperature adjusting means has anelectrical heater.

The present invention further comprises a steam supply portion forvaporizing the processed water from the processed into steam and addingthe steam to raw material supplied to the reformed gas supply portion,wherein the steam supply portion adjusts the addition amount of water sothat the ratio (S/C ratio) between the amount of supplied water and theamount of raw fuel gas ranges from 3 to 4.

In the present invention, the reformed gas supply portion has a COremover for reducing the concentration of carbon monoxide in thereformed gas, and the reformed gas output from the CO remover issupplied to the fuel-cell main body without removing moisture therefrom.

The present invention further comprises water processing means forsubjecting city water to predetermined processing to generate processedwater having low electrical conductivity, and supplying the processedwater thus generated to the processed water supply portion.

The present invention further comprises an exhaust heat recovery portionthat is supplied with high-temperature gas discharged from the fuel-cellmain body and recovers heat generated in the fuel-cell main body throughthe electrochemical reaction between hydrogen in the reformed gas andoxygen in the reactant air.

In the present invention, the exhaust heat recovery portion comprises aheat exchanger in which water is circulated to be heat-exchanged withhigh-temperature gas discharged from the fuel-call main body, and a hotwater tank for stocking hot water from the heat exchanger and supplyingwater to the heat exchanger.

The present invention further comprises a heat exchanger that isattached to the processed water supply portion and performs the heatexchange between the processed water and the water while the processedwater and the water are circulated in the heat exchanger so as not to bemixed with each other.

In the present invention, the exhaust heat recovery portion comprises aheat exchanger in which the processed water from the processed watersupply portion is circulated to be heat-exchanged with high-temperaturegas discharged from the fuel-cell main body, thereby performing exhaustheat recovery.

The present invention further comprises a cooling portion in whichcooling refrigerant is circulated, the cooling portion being attached tothe fuel-cell main body and performing heat exchange with the fuel-cellmain body to cool the fuel-cell main body, wherein heat exchange isperformed between the processed water from the processed water supplymeans and the cooling refrigerant from the cooling portion while theprocessed water and the cooling refrigerant are circulated without beingmixed with each other, thereby recovering heat generated in thefuel-cell main body to the processed water supply portion.

The present invention further comprises a water withdrawing portion forwithdrawing water generated in the fuel-cell main body.

In the present invention, the water withdrawing portion comprises a heatexchanger for performing the heat exchange between discharge gas fromthe fuel-cell main body and water circulated therein to liquefy andwithdraw water from the discharge gas, and a water resupply portion fortemporarily stocking the water withdrawn by the heat exchanger and citywater.

In the present invention, the water resupply portion supplies thestocked water to the processed water supply portion in accordance withthe water level thereof.

In the present invention, the water resupply portion comprises a waterlevel gauge for detecting the water level and controls supply of thecity water to the water resupply portion and supply of stocked water tothe processed water portion in accordance with the detection result ofthe water level gauge.

The present invention further comprises a water processing portiondisposed at the front stage of the water resupply portion or between thewater resupply portion and the processed waster supply portion, thewater processing portion performing predetermined processing on citywater to generate processed water having low electrical conductivity,and supplying the processed water thus generated to the water resupplyportion or the processed water supply portion.

The present invention further comprises a cooling portion which isattached to the fuel-cell main body and in which cooling refrigerant iscirculated to be heat-exchanged with the fuel-cell main body to cool thefuel-cell main body, wherein the processed water from the processedwater means and the cooling refrigerant from the cooling portion areheat-exchanged with each other while the processed water and the coolingrefrigerant are circulated so as not to be mixed with each other,thereby recovering heat generated in the fuel-cell main body to theprocessed waster supply portion.

The present invention further comprises a first processed water supplypath for directly supplying the stocked water of the water resupplyportion to the processed supply portion; a second processed water supplyportion for supplying, through a water processing device for conductingpredetermined processing on the stocked water of the water resupplyportion to generate processed water having low electrical conductivity,the processed water to the processed water supply portion; a waterquality detector for detecting the water quality of the stocked water ofthe water resupply portion; and a processed water path switching portionfor selecting one path of the first processed water supply path and thesecond processed water supply path and supplying the processed water tothe processed water portion, which are disposed between the waterresupply portion and the processed water supply portion.

In the present invention, the water quality detector comprises aconductometric device of water or water quality sensor.

The present invention further comprises: a first processed water supplypath for directly supplying the stocked water of the water resupplyportion to the processed supply portion; a second processed water supplyportion for supplying, through a water processing device for conductingpredetermined processing on the stocked water of the water resupplyportion to generate processed water having low electrical conductivity,the processed water to the processed water supply portion; and aprocessed water path switching portion for selecting one path of thefirst processed water supply path and the second processed water supplypath at a predetermined time cycle and supplying the processed water tothe processed water portion, which are disposed between the waterresupply portion and the processed water supply portion.

In the present invention, the water processing portion further includesa mechanism for heating the processed water of the processed watersupply portion by heat generated from a power generation system havingthe fuel cell.

In the present invention, the mechanism has a heat exchanger foradjusting the temperature of the processed water of the processed watersupply portion through heat exchange using the heat generated in thepower generating system.

The present invention further comprises a heat exchanger that isattached to the processed water supply portion and in which theprocessed water in the processed water supply portion is circulated,wherein the temperature of the processed water in the processed watersupply portion is adjusted through the heat exchange in the heatexchanger.

The present invention is characterized by comprising: a fuel-cell mainbody for-performing power generation through the electrochemicalreaction between hydrogen in reformed gas and oxygen in reactant air; areactant air supply portion for supplying the reactant air to thefuel-cell main body; a reformed gas supply portion for supplying thereformed gas to the fuel-cell main body; and a processed water supplyportion for supplying processed water to at least one of the reformedgas supply portion and the fuel-cell main body, characterized in thatthe reactant air supplied from the reactant air supply portion is passedthrough the processed water stocked in the processed water supplyportion, and then the humidified reactant air is supplied to thefuel-cell main body.

The present invention is characterized in that reactant air used at anair electrode of a solid polymer type fuel cell is humidified withcooling water of the fuel cell or a power generation system having thefuel cell and then supplied to the air electrode.

The present invention is characterized in that reactant air used at anair electrode of a solid polymer type fuel cell is humidified withcooling water circulated in the fuel cell, and then supplied to the airelectrode.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a systematic diagram showing a first embodiment of a powergenerating system equipped with a solid polymer type fuel cell accordingto the present invention;

FIG. 2 is a systematic diagram showing a second embodiment of the powergenerating system equipped with the solid polymer fuel cell according tothe present invention;

FIG. 3 is a systematic diagram showing a third embodiment of the powergenerating system equipped with the solid polymer fuel cell according tothe present invention;

FIG. 4 is a systematic diagram showing a fourth embodiment of the powergenerating system equipped with the solid polymer fuel cell according tothe present invention;

FIG. 5 is a systematic diagram showing a fifth embodiment of the powergenerating system equipped with the solid polymer fuel cell according tothe present invention; and

FIG. 6 is a systematic diagram showing withdrawal of processed water andthe construction of the main part of a resupplying device in the solidpolymer type fuel cell according to the third embodiment of the presentinvention.

BEST MODES FOR IMPLEMENTING THE INVENTION

The present invention will be described in more detail with reference tothe accompanying drawings.

The following embodiments will be described while focusing on a casewhere a solid polymer type fuel cell (in the following description,hydrogen generating system, electrochemical reaction system (fuel cellmain body), a cooling system, etc. will collectively means a fuel cell)is used in a power generating system for a domestic compact power sourceor the like. Further, for the sake of simplicity of the description on acase where reformed gas containing hydrogen and air containing oxygenare used as gas for electrode reaction supplied to the main body of afuel cell, the air to be supplied to an electrode will be particularlyreferred to as reactant air, and the electrode to which the reactant airis supplied will be referred to as an air electrode. Further, in thepresent invention, the electrode reaction gas is not necessarily limitedto the above materials.

A first embodiment of a solid polymer type fuel cell according to thepresent invention will be described with reference to FIG. 1.

As shown in FIG. 1, a power generating system GS using the fuel cellaccording to the first embodiment is equipped with a heat recoverydevice RD in addition to the fuel cell, for example. The heat recoverydevice RD and the fuel cell are linked to each other through a water orheat medium circulating path containing a hot water reservoir tank 50and a water processing device 51 using an ion exchange resin or thelike, etc.

City water is supplied to the water processing device 51. The city wateris reformed, for example, to processed water having low electricconductivity (which will be referred to as processed water in thepresent invention) so that it does not effect the insulation of the fuelcell in the water processing device 51, and the processed water issupplied through a processed water pipe 152 into a water tank 21described later.

The fuel cell according to this embodiment is constructed by a devicefor supplying reformed gas for electrode reaction (hereinafter referredto as reformed gas) which comprises a desulfurizer 2, a reformer 3, a COshift converter 4, a CO remover 5, etc., a fuel-cell main body 6comprising a fuel electrode, an air electrode and an ion exchangemembrane sandwiched therebetween, a reactant air (air) supplying devicecomprising an air pump 11, a water tank 21, etc., and a fuel cellcooling device comprising the water tank 21, a pump 48, a coolingportion 6 c, etc.

The power generated in the fuel cell is boosted by a DC/DC converter(not shown), and it is connected to a commercial power source through apower distribution system linked inverter (not shown). On the otherhand, the power from the commercial power source is supplied a power forillumination, air conditioners and other electronic equipment of houses,offices, etc.

In a power generating system GS using such a fuel cell, effective use ofenergy possessed by fuel used in a fuel cell is promoted, for example bywithdrawing hot water from city water with heat generated at the powergeneration time of the fuel cell, stocking the hot water in a hot waterreservoir tank 50 and supplying the hot water to a bath, a kitchen, etc.

In the reformed gas supply device of the fuel cell described above, rawfuel gas such as natural gas, city gas, methanol, LPG, butane or thelike is supplied to the desulfurizer 2 through a fuel pipe 1 to removesulfur components from the raw fuel gas. When the raw fuel gas passedthrough the desulfurizer 2 is boosted in pressure by a booster pump 10and supplied to the reformer 3, the raw fuel gas is confluent with steamachieved by passing water from the water tank 21 through the water pump22 and then heating the water in a heat exchanger 17, and then suppliedto the reformer 3.

In the reformer 3 is generated reformed gas containing hydrogen, carbondioxide and carbon monoxide. The gas passed through the reformer 3 issupplied to the CO shift converter 4, and monoxide contained in thereformed gas is converted to carbon dioxide in the CO shift converter 4.The gas passed through the CO shift converter 4 is supplied to the COremover 5, and unconverted carbon monoxide contained in the gas passedthrough the CO shift converter 4 is oxidized and converted to carbondioxide in the CO remover 5. The gas (reformed gas) passed through theCO remover 5, in which the concentration of carbon monoxide is reducedto 10 ppm or less and the hydrogen concentration is high, is supplied tothe fuel electrode of the fuel-cell main body 6.

In the fuel cell having the above construction, power generation isperformed through the chemical reaction between high-concentrationhydrogen contained in the reformed gas and oxygen in the air which issupplied through the air pump 11, the water tank 21, etc. and thensupplied to the air electrode 6 k, and heat based on the electrochemicalreaction occurs. The cooling device of the fuel cell is disposed injuxtaposition with the fuel electrode 6 a and the air electrode 6 k ofthe fuel-cell main body 6, and the processed water in the water tank 21is circulated as cooling water into the cooling portion 6 c by using thepump 48 to control the temperature in the fuel-cell main body 6 with thecooling water so that the temperature is kept to a temperature suitablefor power generation.

Since the chemical reaction in the reformer 3 is an endothermalreaction, it is necessary to make the chemical reaction while heating atall times by a burner 12. The burner 12 is equipped as heating means.The burner 12 is supplied with raw fuel gas through a fuel pipe 13, andfurther supplied with combustion air through a fan 14. In addition, theburner 12 is supplied with non-reacted hydrogen gas (off gas) dischargedfrom the fuel electrode 6 a through a pipe 15. In FIG. 1, the raw fuelsupplied to the burner 12 is directly supplied from the fuel pipe 1,however, it may be supplied to the burner 12 through the desulfurizer 2.

At the time when the system GS is started, the fuel gas is supplied tothe burner 12 through the fuel pipe 13, and the combustion air is alsosupplied through the fan 14 to thereby perform combustion. When theoperation of the fuel-cell main body 6 is stabilized after the start,the supply of the fuel gas from the fuel pipe 13 is interrupted, and offgas is supplied as fuel gas to the burner 12 through the pipe 15.

On the other hand, since the chemical reaction made in the CO shiftconverter 4, the CO remover 5 is an exothermal reaction, in the COremover 5 a burner (not shown) is made to induce combustion only at thetime when the system is started, thereby generating combustion gas, andat this time the temperature of the CO remover 5 rises up to theexothermal reaction temperature by the heat of the combustion gas thusgenerated. Thereafter, the reaction temperature is kept by the heat ofthe exothermal reaction being made in the CO remover 5. As occasiondemands, the CO shift converter 4 and the CO remover 5 are controlled tobe cooled from the external to prevent the temperature thereof frombeing increased to the reaction temperature or more. Once thetemperature is increased to the reaction temperature, the coolingcontrol is carried out so that the temperature is prevented fromexceeding the reaction temperature due to the heat of the exothermalreaction.

As described above, the reaction temperature is kept in the reformer 3,the CO shift converter 4, the CO remover and the fuel-cell main body 6so that the prescribed chemical reactions and the power generation canbe continued.

In the reactant air supply device, the reactant air fed into the watertank 21 by the pump 11 is humidified in the water tank 21 before it issupplied to the air electrode 6 k of the fuel-cell main body 6.Reference numeral 29 represents an auxiliary pump when such reactant airis supplied to the air electrode 6 k. The auxiliary pump 29 may beomitted.

As described later, the humidification of the reactant air is performedby forming a vapor-phase portion 53, supplying air from the air pump 11into the water in the water tank 21 in which the water temperature iskept within a set temperature range, and feeding out bubbles in thewater to the vapor-phase portion 53 while bubbling the water. Asdescribed above, the reactant air which has been provided with moistureis supplied from the water tank 21 to the air electrode 6 k of thefuel-cell main body 6 so that the reaction in the fuel-cell main bodycan be properly kept.

Addition of water to the reformed gas to be supplied to the fuelelectrode 6 a of the fuel-cell main body 6 of the present invention isadjusted by adjusting the amount of processed water which is passed fromthe water tank 21 through the pump 22 and the heat exchanger 17 to thereformer 3. Since the processed water supplied to the heat exchanger 17is vaporized into steam, if the ratio (S/C ratio) between the amount ofthe steam and the amount the raw fuel gas which are supplied to thereformer 3 is set to a higher value than the conventional S/C ratio of 2to 3, for example, set to 3 to 4 in S/C ratio to thereby increase thewater amount contained in the reformed gas output from the reformer 3and also the reformed gas output from the CO remover 5 is directlysupplied to the fuel-cell main body 6 without removing the moisture fromthe reformed gas so that no moisture is lost from high-concentrationhydrogen gas from which CO is removed (that is, the S/C ratio is set toa high value), proper moisture could be provided to the reformed gas tobe supplied to the fuel electrode 6 a of the fuel-cell main body withoutspecially providing an independent humidifying device for humidifyingthe fuel gas for reaction.

When there is a risk that the reformed gas is supplied into thefuel-cell main body 6 while the temperature of the reformed gas is keptto a high value which is substantially equal to the temperature of thegas output from the CO remover 5 as in the case of a cell having astructure in which the pipe length between the CO remover 5 and thefuel-cell main body 6 is short, and thus the temperature of thefuel-cell main body 6 is excessively increased, so that the powergeneration function is lowered and the electrode portion, etc. of thecell are damaged, it is preferable that a heat exchanger (not shown) isequipped in a pipe 70 between the CO remover 5 and the fuel-cell mainbody 6 and water from the water tank 21 or the like is made to flow intothe heat exchanger to heat-exchange the water with the reformed gas,thereby adjusting the temperature of the reformed gas.

If the temperature of the reformed gas flowing into the fuel-cell mainbody 6 is kept to, for example, 80° C. or less by using such a heatexchanger as described above, the reformed gas could be supplied to thefuel-cell main body 6 under the state that the humidity of the reformedgas is set so that the saturation steam pressure at this temperature issubstantially kept. Therefore, moisturizing of reformed gas (adjustmentof humidity) can be implemented on various types of fuel cells havingvarious structures with no thermal obstruction.

Not only the cooling water circulated in the fuel-cell main body 6 flowsthrough the water pipe into the water tank 21, but also water or thelike discharged from the fuel electrode 6 a and the air electrode 6 k ofthe fuel-cell main body 6 is stocked in the water tank 21. The reactantair to be supplied to the fuel-cell main body 6 may be humidified withsuch water and then supplied to the air electrode 6 k or may becirculated in the cooling portion 6 c to cool the fuel-cell main body 6.

The water returned into the water tank 21 as described above is notnecessarily limited to the water from the fuel-cell main body 6. Ifwater is substantially close to the processed water generated from thepower generating system having the fuel cell as described above, thewater is returned to the water tank 21 again to be recycled as water forhumidification and supplied to the air electrode.

Therefore, the water tank 21 is equipped with a liquid level controllerLC for keeping the water level of the processed water so that an airportion (vapor-phase portion) 53 is formed at the upper portion in thetank at all times, and a temperature adjusting means TC for keeping thewater temperature in the water tank 21 within a set temperature range.

The liquid level controller LC is equipped with a controller for a waterlevel gauge 54 and a motor operated valve 56, and serves to control theamount of the processed water in the water tank 21 so as to stock theprocessed water in the water tank 21 and form the vapor-phase portion 53at the upper portion of the water tank while monitoring the water amountin the water tank 21 at all times so that the reactant air is properlyhumidified while passing through the water tank 21 and then supplied tothe fuel-cell main body 6. The liquid level controller LC keeps thewater level to a set value by controlling the pump for circulating waterin the fuel cell or the heat exchanger of the power generating device GSusing the fuel cell together with the temperature adjusting means TC. Ifthe water level in the water tank cannot be kept to the set value undersuch a control operation, city water supplied from a water tap or thelike through a water pipe 52 is processed by an ion exchange device ofthe processing device 51 to achieve processed water, and the processedwater thus achieved is introduced into the water tank 21 by adjustingthe opening degree of the motor operated valve 56 so that the waterlevel in the water tank 21 is kept within a set range.

Reference numeral 55 represents a wave attenuating plate with which thedetection of the water level by the water level gauge 54 mounted in thewater tank 21 is prevented from being unstable due to fluctuation of thewater surface which is caused by discharge of air supplied from the pump11 into the water in the water tank 21.

The temperature adjusting means TC serves to adjust the temperature ofthe processed water in the water tank 21 so that the upper limit valueof the temperature is varied in accordance with the operationtemperature of the fuel cell, whereby the reactant air is properlyhumidified in the water tank 21 during passage thereof through the watertank 21 when the reactant air is supplied to the air electrode 6 k ofthe fuel-cell main body 6. For example, the processed water is keptwithin the temperature range (set temperature) from 60° C. to 80° C.This water temperature control is performed by controlling a heatingdevice 63 such as an electrical heater or the like which is equipped tothe water tank 21, as occasion demands. The water temperature control iscarried out by the temperature adjusting device TC such that the watertemperature is set to a high value when it is necessary to provide alarge amount of water to the reactant air or it is set to a low valuewhen the cell can operate with even a small amount of water, that is,the temperature of the processed water is controlled so that thereactant air is provided with moisture suitable for the electrodestructure or the cell structure used in the fuel cell.

A heat exchanger 18 is connected between the reformer 3 and the CO shiftconverter 4 and a heat exchanger 19 is connected between the CO shiftconverter 4 and the CO remover 5, and the processed water in the watertank 21 is circulated into the heat exchangers 18, 19 through pumps 23,24 respectively to cool the gas passed through each of the reformer 3and the CO shift converter 4 with the water.

A heat exchanger 17 is connected to an exhaust system 31 of the reformer3, and the water from the water tank 21 is vaporized into steam by theheat exchanger 17, and the steam thus achieved is mixed with raw fuelgas passed through a pump 10 and then the mixture is supplied to thereformer 3. Further, another heat exchanger 32 is connected to theexhaust system 31 in addition to the heat exchanger 17, and water fromthe hot water reservoir tank 50 is circulated in the heat exchanger 32through a pump 33 to perform exhaust heat recovery.

Reference numeral 34 represents a process gas (PG) burner. when theoperation of the power generating system having the fuel cell isstarted, the PG burner 34 burns the reformed gas passed through thereformer 3, the CO shift converter 4 and the CO remover 5 until thereformed gas can be supplied to the fuel-cell main body 6 as gas havinga stable and suitable composition for the operation of the fuel-cellmain body, and the reformed gas is supplied into the fuel-cell main body6 to perform the power generation after the operation of each reactor isstabilized. Off-gas which is not available for the power generation inthe fuel-cell main body 6 is initially fed to the PG burner 34 to beburned. After the temperature of the fuel-cell main body 6 isstabilized, off-gas from the fuel-cell main body 6 is passed through apipe 15 and introduced to the burner 12 of the reformer 3 to be burned.

Here, the control system for the PG burner 34 will be described.

After the power generating system of this embodiment is started, anopening/dosing valve 91 is closed and an opening/closing valve 36 isopened until each reactor is stabilized in temperature. Accordingly, thereformed gas is supplied through a pipe 35 and the opening/closing valve36 into the PG burner 34. When each reactor is stabilized intemperature, the opening/closing valves 91 and 39 are opened and theopening/closing valves 36 and 92 are closed until the temperature of thefuel-cell main body 6 is stabilized, so that the reformed gas issupplied to the burner 34 through a pipe 38 and the opening/dosing valve39 to be burned. Specifically, when the temperature of the fuel-cellmain body 6 is increased to a predetermined temperature (for example,60° C.) or more and the reformer 3, the CO shift converter 4, the COremover 5, etc. are stabilized in temperature, the opening/closingvalves 91, 39 are opened and the opening/closing valves 36, 92 areclosed until the temperature of the fuel-cell main body 6 is stabilizedin a temperature area near to an operation temperature (for example,from 70° C. to 80° C.), so that the fuel gas is supplied to the PGburner 34 through the pipe 38 and the opening/closing valve 39 to beburned.

When the temperature of the fuel cell 6 is stabilized at the operationtemperature and the power generation is enabled to be continuouslycarried out, the opening/closing valves 91, 92 are opened while theopening/closing valves 36, 39 are closed, and the power generation iscarried out in the fuel-cell main body 6. Off-gas which does notcontribute to the reaction in the fuel-cell main body 6 is passedthrough the pipe 15 and supplied to the burner 12 to be burned.

A heat exchanger 46 is connected to the exhaust system 45 of the PGburner 34, and the water from the hot water reservoir tank 50 iscirculated in the heat exchanger 46 through a pump 47 to perform exhaustheat recovery.

City water is supplied through a water pipe 61 into the hot waterreservoir tank 50. The city water supplied in the hot water reservoirtank 50 is heated by the recovered exhaust heat of the fuel cell powergenerating system (the power generating system using the solid polymertype fuel cell) so that the temperature thereof is increased to aprescribed temperature, and the hot water thus heated is suppliedthrough a hot water supply pipe 62 to the outside.

FIG. 2 is a diagram showing a second embodiment of the power generatingsystem using the solid polymer type fuel cell according to the presentinvention.

This embodiment is different from the first embodiment shown in FIG. 1in that it is equipped with a heat recovery device (heat exchanger 27)for recovering heat from the reactant air discharged from the airelectrode 6 k of the fuel-cell main body 6 and a heat exchanger 41 whichis disposed between the water tank 21 and the hot water reservoir tank50 to perform mutual heat exchange between the water tank 21 and the hotwater reservoir tank 50. Since the other elements are the same as shownin FIG. 1, these elements are represented by the same reference numeralsand symbols, and the description thereof is omitted.

An exhaust heat recovery has the heat exchangers 18, 19, 27, 32, 41 and46 and the pumps 23, 24, 28, 33, 42, 43, 47, etc., and the exhaust heatrecovery is performed by circulating the processed water of the watertank 21 and the hot water of the hot water reservoir tank 50 throughthese pumps into the heat exchangers.

Reference numeral 27 represents an exhaust-heat recovery heat exchangerequipped to a reactant air exhaust system 26 of the fuel-cell main body6. City water from the hot water reservoir tank 50 is circulated in theheat exchanger 27 by the pump 28 to recover heat from the gas of 70° C.to 80° C. discharged from the air electrode 6 k, and the hot city waterthus heat-exchanged is stocked in the hot water reservoir tank 50. Atthe same time, the gas discharged from the fuel-cell main body 6 iscooled.

Reference numeral 41 represents the heat exchanger equipped to the watertank 21, and the processed water of the water tank 1 is circulated inthe heat exchanger through the pump 42, and also the city water from thehot water reservoir tank 50 is circulated in the heat exchanger 41through the pump 43 so that the processed water and the city water arenot mixed with each other. The city water of the hot water reservoirtank and the processed water of the water tank 21 are properlyheat-exchanged with each other through the heat exchanger 41. Thetemperature of the processed water of the water tank 21 can be adjustedthrough the heat exchange of the heat exchanger 41. In this case, thetemperature adjusting means TC shown in FIG. 1 may be omitted.

In the embodiment shown in FIG. 2, the water tank 21 is used to humidifythe reactant air to be supplied to the electrode. Therefore, it is givenpriority to keep the water temperature in the water tank within a settemperature range so that the air to be supplied to the air electrode 6k through the water tank 21 is kept properly humidified. When thetemperature in the water tank 21 is excessively high, the pump 42 isdriven and the pump 42, the pump 43, etc. are controlled so that heattransfer to the hot water reservoir tank 50 is enabled.

FIG. 3 is a diagram showing a third embodiment according to the powergenerating system using the solid polymer type fuel cell according tothe present invention.

The third embodiment of FIG. 3 is different from the first embodimentshown in FIG. 1 in that an exhaust heat recovery device for dischargegas from the air electrode 6 k of the fuel-cell main body 6 is equippedand cooling medium such as refrigerant, organic solvent or the like isavailable to cool the fuel-cell main body 6. The other elements are thesame as shown in FIG. 1. Therefore, the same elements are represented bythe same reference numerals and symbols, and the description thereof isomitted.

An exhaust heat recovery device according to this embodiment has theheat exchangers 18, 19, 32, 46, 58 and 64 and the pumps 23, 24, 33, 47,59, 66, etc., and performs the exhaust heat recovery by circulating theprocessed water of the water tank 21 and the hot water of the hot waterreservoir tank 50 in the heat exchangers through the pumps.

Reference numeral 58 represents a heat exchanger equipped to the coolingportion 6 c. Organic cooling medium such as ethylene glycol or the likeis circulated in the heat exchanger 58 by a pump 57 to cool the insideof the fuel-cell main body. Further, the processed water of the watertank 21 is circulated in the heat exchanger 58 by the pump 59 so thatthe processed water is not mixed with the organic cooling medium, andthus the heat of the cooling portion 6 c of the fuel cell is recoveredto the water tank 21.

By using such organic cooling medium to cool the fuel cell, theelectrodes of the cell can be efficiently cooled, and the operationtemperature of the cell can be kept under a high power-generationefficiency state. In addition, the temperature of the water of the watertank 21 which is used to humidify the gas (air) to be supplied to theelectrode can be controlled by the temperature adjusting device TC sothat the temperature is kept within a set temperature range.

Reference numeral 64 represents a heat exchanger for recovering heatfrom the discharge gas discharged from the air electrode 6 k of thefuel-cell main body 6. The processed water of the water tank 21 iscirculated in the heat exchanger 64 through the pipe 65 by the pump 66to recover the heat of the discharge gas to the water tank 21.

FIG. 4 shows a fourth embodiment of the power generating system usingthe solid polymer type fuel cell according to the present invention. Inthe embodiment shown in FIG. 4, the same parts as the first embodimentshown in FIG. 1 are represented by the same reference numerals. Theduplicative description on the same parts is omitted, and only thedifferent parts will be described.

The following embodiment of the present invention is characterized inthat a mechanism using water generated in the fuel electrode and the airelectrode of the fuel-cell main body is further equipped to the solidpolymer type fuel cell of each of the first to third embodimentsdescribed above.

In the fuel cell according to the fourth embodiment shown in FIG. 4, thewater which is supplied and passed through the heat exchangers 18, 19 bythe pumps 23, 24 is returned into the processed water tank 21, and thecooling water which is circulated in the cooling portion 6 c of thefuel-cell main body by the pump 48 and passed through the water pipe 73flows into the processed water tank 21. Further, the processed watertank 21 is connected to a processed water resupply device 68 forresupplying water to the processed water tank 21. The processed waterresupply device 68 comprises a motor operated valve 56, a water supplytank 67, a pump 74, etc.

The water supply tank 67 is a tank for temporarily stocking watergenerated in a city water resupply device 69 and the fuel-cell main body6 and supplying the water to the processed water tank 21.

As the water generated from the fuel-cell main body 6 is withdrawn drainwater achieved by introducing the steam-contained gas discharged fromthe air electrode 6 k of the fuel-cell main body 6 to a heat exchanger71 and then cooling the heat exchanger 71 with the water circulatedbetween the heat exchanger 71 and the hot water reservoir tank 50 by apump 72, and also water contained in the gas discharged from the fuelelectrode 6 a.

The water withdrawn into the water supply tank 67 is not necessarilylimited to the water generated from the fuel-cell main body 6, and itmay be drain water generated from the power generating system GS havingthe fuel cell. Any water is temporarily stocked in the water supply tank67 and then supplied to the processed water tank 21.

The city water resupply device 69 is connected to a water (city water)source 78 through a water pipe 52 having a motor operated valve 76. Whena water level gauge 79 detects reduction of the water level because thewater amount in the water supply tank 67 is reduced like a case wherethe amount of water supplied from the water supply tank 67 into theprocessed water tank 21 is larger than the amount of water flowing intothe water supply tank 67 from the fuel-cell main body 6, etc. asdescribed above, a liquid level controller 77 of the city water resupplydevice 69 opens the motor operated valve 76 to supply the city waterthrough the water pipe 52 and the water processing device 51 into thewater supply tank 67 by using the water pressure of the water source 78,thereby keeping the water amount which does not obstruct supply of waterto the processed water tank 21.

In this embodiment, the liquid level controller LC has a controller forthe water level gauge 54 and the motor operated valve 56 to monitor thewater amount in the water tank 21 at all times. In order to properlyhumidify the reactant air when the reactant air passes through the watertank 21 and then supply the reactant air thus humidified to the fuelcell 6, the amount of the processed water is controlled to stock theprocessed water in the tank 21 and form the vapor-phase portion 53 atthe upper portion of the tank. When the set water level in the watertank cannot be maintained, the driving of the pump 74 is started and theopening degree of the motor operated valve 56 is adjusted to introducethe processed water from the water supply tank 67, thereby keeping theset range of the water level in the water tank 21.

FIG. 5 is a diagram showing a fifth embodiment of the power generationsystem using the solid polymer type fuel cell according to the presentinvention.

The embodiment of FIG. 5 is different from the embodiment shown in FIG.4 in that refrigerant, organic solvent or the like may be used ascooling medium for cooling the fuel-cell main body 6 and the waterprocessing device 51 is disposed between the water supply tank 67 andthe processed water tank 21. The construction of the other parts is thesame as that shown in FIG. 1. Therefore, these parts are represented bythe same reference numerals, and the description thereof is omitted.

In the solid polymer type fuel cell having the processed water resupplydevice 68 according to the embodiment of FIG. 5, reference numeral 58represents a heat exchange equipped to the cooling portion 6 c of thefuel-cell main body 6, and organic cooling medium such as ethyleneglycol or the like is circuited in the heat exchanger 58 by the pump 57to cool the inside of the fuel cell.

Further, the processed water of the processed water tank 21 iscirculated in the heat exchanger 58 by the pump 59 so that the processedwater is not mixed with the organic cooling medium, whereby heat of thecooling portion 6 c of the fuel cell is recovered to the processed watertank 21.

By using the organic cooling medium to cool the fuel cell, theelectrodes of the cell can be effectively cooled to keep the operationtemperature of the cell under a high power generation efficiency state.

Reference numeral 71 represents a heat exchanger to recover heat andwithdraw water from the gas discharged from the air electrode 6 k of thefuel-cell main body. Water of the hot water reservoir tank 50 iscirculated in the heat exchanger 71 by a pump 72, and heat achieved fromthe circulated water is stocked in the hot water reservoir tank 50. Inaddition, drain water condensed from the cooled discharge gas is passedthrough a pipe 170 and withdrawn to the water supply tank 67.

In the processed water resupply device 68 of the embodiment shown inFIG. 5, the water processed device 51 is disposed between the watersupply tank 67 and the processed water tank 21, particularly between thepump 74 and the motor operated valve 56. Therefore, when the liquidlevel controller LC detects lack of the water amount in the processedwater tank 21 by the water level gauge 54 to open the motor operatedvalve 56 and start the driving of the pump 74, the overall waterresupplied from the water supply tank 67 is necessarily improved inwater quality by the water processed device 51, and then supplied to theprocessed water tank 21.

According to the processed water resupply device 68 used for the cellthe embodiment of FIG. 5, on the assumption of the fuel cell having sucha structure that a large amount of water is not lost by the operation ofthe fuel cell, sufficient water can be withdrawn from the cell and mostof water thus withdrawn is not polluted, the overall resupply water tobe supplied to the processed water tank 21 is passed through the waterprocessed device 51, and the processing water supply device forwithdrawing and resupplying water is constructed by the simplestconstruction.

When the amount of water from the fuel cell or the power generationsystem or the drain water withdrawn is reduced due to driving the of thefuel cell 6, the liquid level controller 77 of the water supply tank 67controls the motor operated matter to resupply city water from the watersource 78 into the water tank supply 67 as in the case of the embodimentshown in FIG. 4, and the city water is supplied to the processed watertank 21 together with the city water to complement the lack of water ofthe cell, etc.

FIG. 6 is a diagram showing the main part for water withdrawal andsupply in a sixth embodiment of the power generating system using thesolid polymer type fuel cell according to the present invention.

The embodiment of FIG. 6 is different from the embodiments shown inFIGS. 4 and 5 in that there is equipped a water supply tank fortemporarily stocking water generated in the fuel cell, etc. through apipe 170 and the water is passed through the water processing device 51only when the water quality of water to be supplied from the watersupply tank 67 to the processed water tank 21 is lowered. The otherparts are the same as the construction shown in FIGS. 4 and 5.Therefore, the same parts are represented by the same reference numeralsand symbols, and the description thereof is omitted.

In the solid polymer type fuel cell having the processed water resupplydevice 68 according to the embodiment shown in FIG. 6, reference numeral80 represents a water quality sensor fixed to a water outlet pipe 81 ofthe water supply tank, reference numeral 82 represents a motor operatedvalve for controlling water passage through the water processing device51, which bypasses the motor operated valve 56, and reference numeral 83represents a check valve for preventing counter flow of water from awater supply pipe 84 at the processed waster tank 21 side to the waterprocessing device 51 side. The liquid level controller LC of theprocessed water tank 21 receives signals from the water level gauge 54and the water quality sensor 80 and controls the operation of the pump74 and the motor operated valves 56 and 82 so that water having waterquality required for the fuel cell, etc. is supplied from the watersupply tank 67.

In the embodiment shown in FIG. 6, when the water quality of waterresupplied from the water supply tank 67 to the processed water tank 21does not obstruct the operation of the fuel cell, etc., the liquid levelcontroller LC receives a signal from the water level gauge 54 to operatethe pump 74 and the motor operated valve 56, and supplies the waterhaving the needed water quality from the water supply tank 67 to thetank 21 while bypassing the water processing device 51.

Conversely, when the water quality of water to be resupplied is loweredto the extent that it may influence the operation of the fuel cell,etc., the liquid level controller LC receives a signal from the waterlevel gauge 54 to operate the pump 74 and the motor operated valve 82(the motor operated valve 56 is closed), and controls the equipment sothat water having the water quality needed after the water processing iscarried out in the water processing device 51 is supplied to theprocessed water tank 21.

The judgment on the water quality may be made by using a conductometricdevice (not shown) or the water quality sensor 80 every time water issupplied from the water supply tank 67. However, when the constructionof the equipment is simplified, in place of use of a sensor such as aconductometric device or the like, there may be used a method ofdetermining a time cycle estimated to be needed for the water qualityimproving processing on the basis of the driving time of the fuel cell 6and other control data, determining the driving time every time cycleand opening the motor operated valve 82 to pass water through the waterprocessing device 51.

In the solid polymer type fuel cell according to this embodiment, on theassumption that the drain water, etc. generated in the cell have highwater quality to the extent that it can be directly resupplied andrecycled for humidification of air, reformation of fuel gas and coolingof the cell, when water processing is required during some cycles of thewater supplying and circulating operation of supplying water from thewater supply tank 67 to the processed water tank 21, the drain water,etc. are passed through the water processing device 51 and then suppliedto the processed water tank 21.

Accordingly, the using frequency of the water processing device used inthe solid polymer type fuel cell and the water passage time through theion exchange resin are reduced at the maximum to increase the lifetimethereof, so that a labor needed to exchange the ion exchange resin, etc.and a labor need for maintenance of the solid polymer type fuel cell canbe reduced.

As described above, in the solid polymer type fuel cell according to thepresent invention, the water tank for stocking cooling water used tocool the fuel cell and the power generation system having the fuel cellis added with the temperature adjusting device and the liquid levelcontroller, and the reactant air is passed through the water tankdescribed above. Accordingly, according to the present invention, thereactant air can be added with moisture (i.e., humidified) and thensupplied to the electrodes of the fuel cell without any independent anddedicated humidifier for humidifying the reactant air.

Further, according to the present invention, a water circulating deviceand a water withdrawing device for cooling and heat recovery which areused in this type of conventional water tank can be almost directly usedfor the processed water resupply control and the processed waterwithdrawal for humidification of gas. Therefore, unlike a vapor/waterseparating device for generating steam, a solid polymer type fuel cellhaving a humidifying device which can simply humidify the reactant aircan be provided.

In the solid polymer type fuel cell thus constructed and the powergenerating system having the solid polymer type fuel cell thusconstructed, a co-generation system for power generation and heatapplication can be easily established. Therefore, not only theefficiency of power generation alone can be enhanced, but also highlyeffective use of energy of fuel to be supplied to this system can bepromoted. Therefore, high total heat efficiency can be achieved, so thatthe consumption amount of raw material can be reduced and the dischargeamount of carbon dioxide can be also reduced.

Particularly when tanks having the function of stocking heat such as thehot water tank and the water tank are designed to mutuallyreceive/deliver heat therebetween, a mechanism of heating the water ofthe water tank with heat occurring in the power generation system havingthe fuel cell can be constructed. Therefore, the reactant gas to besupplied to the electrodes of the fuel-cell main body can be simplyhumidified while the heat of the overall system is effectively used, forexample by using the heat of the system having the fuel cell to heat thewater tank, giving extra heat of the water tank to the hot water tankwhen the heat of the water tank is too much, etc.

Further, in the solid polymer type fuel cell according to the presentinvention, the device for withdrawing water generated in the fuel-cellmain body and recycling the water thus withdrawn for the fuel cellconducts the water processing and supplying the water thus processed tothe fuel cell while monitoring the water quality of the water thuswithdrawn, as occasion demands. Therefore, the use frequency of thewater processing device comprising the ion exchanger, etc. can belimited to the minimum level.

Still further, there can be provided a solid polymer type fuel cellwhich can simplify the water processing in the fuel cell by recyclingthe water generated in the fuel cell at maximum level and thus reducethe troublesome task for maintenance.

In the power generation system having the solid polymer type fuel cellthus constructed and the power generation system having the cell, themaintenance of the fuel cell is simplified, so that the co-generation ofpower generation and heat utility can be easily established. Therefore,there can be provided a solid polymer type fuel cell which contributesto not only enhancement of the power generation efficiency of the fuelcell alone, but also the effective recycling of water used in thissystem and the effective use of energy of fuel cell to be supplied.

In the above embodiments, all the processed water from the water tank 21is directly supplied and used as humidifying water for the reformer 3and for the reactant air to be supplied to the air electrode 6 k of thefuel-cell main body. However, the processed water may be supplied toonly a part of the fuel-cell main body (for example, the fuel electrodeor the air electrode) or only the reformer, or it may be indirectlysupplied as in the case of the supply of cooling water to the heatexchanger 58 in the embodiment shown in FIGS. 3, 5.

INDUSTRIAL UTILIZATION

As described above, according to the present invention, equipment suchas a liquid level controller or the like is installed in the water tankof processed water used in the solid polymer type fuel cell to providethe solid polymer type fuel cell with the humidifying mechanism, therebyhumidifying the reactant air. Therefore, the present invention issuitably applied to a fuel cell having no special dedicated humidifierfor humidifying reactant air and also to a power generation systemhaving the fuel cell. Further, the water tank in which the processedwater used for the fuel cell is stocked is organically coupled to thefuel cell or the power generation system having the fuel cell toeffectively use the heat of the fuel cell, so that the water temperaturein the water tank is kept to a temperature suitable for humidification.Therefore, the energy consumption for humidification can be reduced atthe maximum level, and moisture can be added to gas such as reactantgas, etc. to be supplied to the electrodes of the fuel cell while theenergy efficiency of the fuel cell and the overall power generationsystem combined with the fuel cell is enhanced.

1. A solid polymer type fuel cell comprising: a fuel-cell main body forperforming power generation through the electrochemical reaction betweenhydrogen in reformed gas and oxygen in reactant air; a reactant airsupply portion for supplying the reactant air to the fuel-cell mainbody; a reformed gas supply portion for supplying the reformed gas tosaid fuel-cell main body; and a processed water supply portioncomprising a processed water tank for stocking processed water and forsupplying processed water, wherein said processed water tank suppliesthe processed water to said reformed gas supply portion to humidify thereformed gas, humidifies the reactant air supplied from said reactantair supply portion by using the processed water, and supplies thehumidified reactant air to said fuel-cell main body, wherein said watersupply portion comprises water processing means for subjecting water topredetermined processing and supplying the processed water to theprocessed water tank, and wherein said water supply portion furthercomprises a liquid level control portion for keeping the water level ofprocessed water in a predetermined range so that a gas-phase portion isformed in said water tank at all times, the reactant air from saidreactant air supply portion being humidified while passing through saidwater tank and supplied to said fuel-cell main body.
 2. The solidpolymer type fuel cell as claimed in claim 1, further comprising acooling portion for circulating the processed water from said processedwater supply portion to said fuel-cell main body to cool said fuel-cellmain body.
 3. The solid polymer type fuel cell as claimed in claim 1,wherein said liquid level control portion comprises a water level gaugefor detecting the water level of the processed water and a motoroperated valve for controlling supply of the processed water from aprocessed water source into said processed water tank.
 4. The solidpolymer type fuel cell as claimed in claim 1, wherein said processedwater supply portion comprises a processed water tank in which processedwater is stocked, and temperature adjusting means for keeping thetemperature of the processed water in said processed water tank in apredetermined range, wherein the degree of humidification is adjusted bya set temperature when the reactant air from said reactant air supplyportion is humidified while passing through said processed water tank.5. The solid polymer type fuel cell as claimed in claim 4, wherein theupper limit value of the predetermined range of the processed water tobe adjusted by said temperature adjusting means is varied in accordancewith the operation temperature of said fuel cell.
 6. The solid polymertype fuel cell as claimed in claim 5, wherein the predeterminedtemperature range of the processed water to be adjusted by saidtemperature adjusting means ranges from 60°C to 80°C.
 7. The solidpolymer type fuel cell as claimed in claim 4, wherein said temperatureadjusting means has an electrical heater.
 8. The solid polymer type fuelcell as claimed in claim 1, further comprising a steam supply portionfor vaporizing the processed water from said processed into steam andadding the steam to raw material supplied to said reformed gas supplyportion, wherein said steam supply portion adjusts the addition amountof water so that the ratio (S/C ratio) between the amount of suppliedwater and the amount of raw fuel gas ranges from 3to
 4. 9. The solidpolymer type fuel cell as claimed in claim 1, wherein said reformed gassupply portion has a CO remover for reducing the concentration of carbonmonoxide in the reformed gas, and the reformed gas output from said COremover is supplied to said fuel-cell main body without removingmoisture therefrom.
 10. The solid polymer type fuel cell as claimed inclaim 1, further comprising water processing means for subjecting citywater to predetermined processing to generate processed water having lowelectrical conductivity, and supplying the processed water thusgenerated to said processed water supply portion.
 11. The solid polymertype fuel cell as claimed in claim 1, further comprising an exhaust heatrecovery portion that is supplied with high-temperature gas dischargedfrom said fuel-cell main body and recovers heat generated in saidfuel-cell main body through the electrochemical reaction betweenhydrogen in the reformed gas and oxygen in the reactant air.
 12. Thesolid polymer type fuel cell as claimed in claim 11, wherein saidexhaust heat recovery portion comprises a heat exchanger in which wateris circulated to be heat-exchanged with high-temperature gas dischargedfrom said fuel-call main body, and a hot water tank for stocking hotwater from said heat exchanger and supplying water to said heatexchanger.
 13. The solid polymer type fuel cell as claimed in claim 12,further comprising a heat exchanger that is attached to said processedwater supply portion and performs the heat exchange between theprocessed water and the water while the processed water and the waterare circulated in said heat exchanger so as not to be mixed with eachother.
 14. The solid polymer type fuel cell as claimed in claim 11,wherein said exhaust heat recovery portion comprises a heat exchanger inwhich the processed water from said processed water supply portion iscirculated to be heat-exchanged with high-temperature gas dischargedfrom said fuel-cell main body, thereby performing exhaust heat recovery.15. The solid polymer type fuel cell as claimed in claim 1, furthercomprising a cooling portion in which cooling refrigerant is circulated,said cooling portion being attached to said fuel-cell main body andperforming heat exchange with said fuel-cell main body to cool saidfuel-cell main body, wherein heat exchange is performed between theprocessed water from said processed water supply means and the coolingrefrigerant from said cooling portion while the processed water and thecooling refrigerant are circulated without being mixed with each other,thereby recovering heat generated in said fuel-cell main body to saidprocessed water supply portion.
 16. The solid polymer type fuel cell asclaimed in claim 1, further comprising a water withdrawing portion forwithdrawing water generated in said fuel-cell main body.
 17. The solidpolymer type fuel cell as claimed in claim 16, wherein said waterwithdrawing portion comprises a heat exchanger for performing the heatexchange between discharge gas from said fuel-cell main body and watercirculated therein to liquefy and withdraw water from the discharge gas,and a water resupply portion for temporarily stocking the waterwithdrawn by said heat exchanger and city water.
 18. The solid polymertype fuel cell as claimed in claim 17, wherein said water resupplyportion supplies the stocked water to said processed water supplyportion in accordance with the water level thereof.
 19. The solidpolymer type fuel cell as claimed in claim 18, wherein said waterresupply portion comprises a water level gauge for detecting the waterlevel and controls supply of the city water to said water resupplyportion and supply of stocked water to said processed water portion inaccordance with the detection result of said water level gauge.
 20. Thesolid polymer type fuel cell as claimed in claim 17, further comprisinga water processing portion disposed at the front stage of said waterresupply portion or between said water resupply portion and saidprocessed waster supply portion, said water processing portionperforming predetermined processing on city water to generate processedwater having low electrical conductivity, and supplying the processedwater thus generated to said water resupply portion or said processedwater supply portion.
 21. The solid polymer type fuel cell as claimed inclaim 16, further comprising a cooling portion which is attached to saidfuel-cell main body and in which cooling refrigerant is circulated to beheat-exchanged with said fuel-cell main body to cool said fuel-cell mainbody, wherein the processed water from said processed water means andthe cooling refrigerant from said cooling portion are heat-exchangedwith each other while the processed water and the cooling refrigerantare circulated so as not to be mixed with each other, thereby recoveringheat generated in said fuel-cell main body to said processed wastersupply portion.
 22. The solid polymer type fuel cell as claimed in claim17, further comprising: a first processed water supply path for directlysupplying the stocked water of said water resupply portion to saidprocessed supply portion; a second processed water supply portion forsupplying, through a water processing device for conductingpredetermined processing on the stocked water of said water resupplyportion to generate processed water having low electrical conductivity,the processed water to said processed water supply portion; a waterquality detector for detecting the water quality of the stocked water ofsaid water resupply portion; and a processed water path switchingportion for selecting one path of said first processed water supply pathand said second processed water supply path and supplying the processedwater to said processed water portion, which are disposed between saidwater resupply portion and said processed water supply portion.
 23. Thesolid polymer type fuel cell as claimed in claim 22, wherein said waterquality detector comprises a conductometric device of water or waterquality sensor.
 24. The solid polymer type fuel cell as claimed in claim17, further comprising: a first processed water supply path for directlysupplying the stocked water of said water resupply portion to saidprocessed supply portion; a second processed water supply portion forsupplying, through a water processing device for conductingpredetermined processing on the stocked water of said water resupplyportion to generate processed water having low electrical conductivity,the processed water to said processed water supply portion; and aprocessed water path switching portion for selecting one path of saidfirst processed water supply path and said second processed water supplypath at a predetermined time cycle and supplying the processed water tosaid processed water portion, which are disposed between said waterresupply portion and said processed water supply portion.
 25. The solidpolymer type fuel cell as claimed in claim 1, wherein said waterprocessing portion further includes a mechanism for heating theprocessed water of said processed water supply portion by heat generatedfrom a power generation system having said fuel cell.
 26. The solidpolymer type fuel cell as claimed in claim 25, wherein said mechanismhas a heat exchanger for adjusting the temperature of the processedwater of said processed water supply portion through heat exchange usingthe heat generated in said power generating system.
 27. The solidpolymer type fuel cell as claimed in claim 1, further comprising a heatexchanger that is attached to said processed water supply portion and inwhich the processed water in said processed water supply portion iscirculated, wherein the temperature of the processed water in saidprocessed water supply portion is adjusted through the heat exchange insaid heat exchanger.
 28. A solid polymer type fuel cell comprising: afuel-cell main body for performing power generation through theelectrochemical reaction between hydrogen in reformed gas and oxygen inreactant air; a reactant air supply portion for supplying the reactantair to the fuel-cell main body; a reformed gas supply portion forsupplying the reformed gas to said fuel-cell main body; and a processedwater supply portion comprising a processed water tank for stockingprocessed water and for supplying processed water, and a waterprocessing means for subjecting water to predetermined processing andsupplying the processed water to the processed water tank; wherein saidreactant air supply portion communicates with an inlet of the processedwater tank for humidifying the reactant air before the reactant air issupplied to the fuel-cell main body, wherein said process water tankcomprises a first outlet communicating with said reformed gas supplyportion for supplying processed water to said reformed gas supplyportion to humidify the reformed gas, and a second outlet communicatingwith the fuel-cell main body for supplying humidified reactant air tosaid fuel-cell main body, and wherein said processed water supplyportion further comprises a liquid level control portion for keeping thewater level of processed water in a predetermined range so that agas-phase portion is formed in said water tank at all times, thereactant air from said reactant air supply portion being humidifiedwhile passing through said water tank and supplied to said fuel-cellmain body.